I have StopTech slotted and drilled rotors with StopTech pads on my 2002 for a few years now. I like the quick bite of the brakes a lot. For the second time, however, a wobble is coming from the brakes when slow braking. The first time, I had them refinished and the wobble was gone. Now it came back. I am wondering if that is something re-occurring and due to slotted/drilled. there are about 15k miles on the rotors, mainly city driving in hot Nevada.
Are there alternative rotors available which give you a similar bite?
I don't want to put in a complete new set-up like from the Supra.

 

Wait... 15k since the last resurface? Or the resurface was done within the last 15k...?

The SC isn't a light car by any means, and I'm kind of shocked that Lexus didn't put the same large 4 piston fixed calipers on the SC that they put on the LS of the same era. Even the mid 90's LS400s came with 4 piston fixed calipers... god knows why Lexus thought that a car that weighs only 100lbs less than the LS doesn't need similar stopping power....

Anyway, on the topic of calipers, it's possible that one of your pistons is at least partially seized and causing a pad to constantly drag against the rotor, causing heat to constantly build up as you're driving, resulting in a warped rotor. Similarly, one or both of your slide pins on a caliper could be sticking due to being improperly lubricated and resulting in one of your outer pads dragging on the rotor and causing heat buildup, or you could have a pad that's catching on a part of the caliper causing it to stay against the rotor. One of the many reasons why I carry a cheap IR temp gun in my car to is to check for uniform heat/heat dissipation of the rotors and calipers. You can easily check if you have a dragging pad by driving at highway speed for a good 10-20 minutes, then stop and shoot the rotors and calipers with the IR temp gun. If a rotor on one side is more than 30-50 degrees hotter than the rotor on the other side, you can basically guarantee that a pad is dragging and you need to figure out why. It's much less likely, but both front rotors could be affected by a pad dragging.

Another possibility is that your lug nuts are not uniformly torqued/over torqued and causing one or both rotors to warp as they heat up and cool down.

Lastly, I suppose it's possible that you've just warped them due to driving in the heat and not giving them a chance to cool down properly since you're doing mostly city driving... but fact that they're drilled and slotted should have helped somewhat.

Do you have drilled & slotted rotors on both the front and the rear? Is it possible that the vibration you're feeling is from the rear brakes? Does this vibration exist in the steering wheel mostly, or the entire car? If you can't really feel it in the steering wheel, but feel it in the whole car, the rear brakes might be the culprit.

 

He or she does not have stock rotors so don't blame Lexus. The SC does have front calipers that do have two pistons per caliper. So, once again, don't blame Lexus. The biggest problem here is believing that having drilled and slotted rotors have any benefit. They do not. I have a friend that is a certified Mercedes Benz tech and he laughs at the new MB models that have drilled rotors. He agrees that it is just marketing. People think it makes the rotors better some how. The rotor has little to nothing to do with the COF of the pad rotor interface. All the good ones are made from cast iron. Not steel. I have even read that some feel that due to the removal of rotor material the rotor is more prone to failure ie vibration.

 

Been running drilled slotted rotors (R1 Concepts Premier) with Akebono ceramic pads for the last 12k miles. They are performing much better than all the previous combos I had. ( OEM rotors+OEM Pads, OEM rotors+Posi Quiet ceramic pads, Slotted Power Stop rotors+ Posi Quiet Ceramics). No vibrations at all thus far. Touch wood.

 

Huh? I'm not even talking about rotors at all with my statement about Lexus's engineering decisions. Obviously I'm well aware that his rotors are not stock since I know the SC didn't come with cross drilled and slotted rotors. Blame Lexus for what in regard to his dissatisfaction with his non-Lexus rotors?

Again, yes, I'm very well aware what kind of calipers the SC came equipped with. The obvious "flaw" that I guess I'll point out again is that they're floating calipers instead of fixed, in addition to having half the amount of pistons that they could should have given the weight of the vehicle. Having more pistons in a fixed caliper design not only helps to dissipates heat more even across the surface of the rotor, but also across each side of the rotor, thus minimizing the propensity to warp due to uneven heating... not to mention providing better 'bite' as far as pedal feel. I merely made an observation about the design of the braking system. However you decided that I was trying to "blame Lexus" for anything is beyond me...

Who claimed that blank vs cross drilled/slotted rotors have anything to do with coefficient of friction, especially in relation to this thread? The purpose of cross drilled and slotted rotors is increased heat dissipation, but the actual benefit in real world street driving/everyday applications are marginal at best due to lack of speed and subsequent airflow to take advantage of the extra holes and slots, in addition to the genuine lack of truly hard and continuous brake applications to warrant their use. In case you hadn't noticed, the topic of discussion in this thread is related to a "wobble" caused by warped rotors, which is a result of heat a vast majority of the time, and likely a main reason the OP purchased the drilled/slotted rotors.

 

Here an up-date: Went to my favorite Brake-Shop and they confirmed that there is a judder and recommended to mill them yet again, after about 3,000 since the last. Pads in front down to 20% which is ok, but as rotors had been milled before they considered them too thin to redo. The rear is still fine for rotors and pads. That translates that as the rotors and the pads came on at the same time, the pads outlasted the rotors, that is new to me. I therefore contacted StopTech. Helpful person on the phone said that the judder may be caused by a mismatched brake-pad to my driving style. I have the harder ones on it now and am not driving aggressive enough ( i don't do any autocross or track at all, just spirited driving in the city) to ensure an even layer of the pad residue on the rotor resulting in high spots on the rotor. He recommended a softer pad. This is the first time i heard that and am inclined to get new pads and obviously new rotors for the front as I don't want to go back to stock. Any comments?

Another questions: how many pistons do our front brakes have?

 

3,000?!? Good googly-moogly! I don't think I've ever even heard of someone needing rotor resurfacing more frequently than oil changes. Stating the obvious here, but that is NUTS and very much so not normal considering that you don't track your car

I figure you already worked this part out, but the fact that you went with harder pads is why the rotors are wearing out first. As you also probably already know, generally rotors are harder than pads, so pads wear out before the rotors. If you chose a pad with super hard friction material but used rotors designed for softer pads... well, something's gotta give.

Listen to his recommendation lol...go with a softer pad. This goes hand-in-hand with what I said just above, as well as your initial reason for posting this thread - your vibration/"wobble". As I stated above, a hard pad is not only going to 'scrub' away the rotor more quickly than a softer pad, but a byproduct of that is that a larger portion of the heat generated under braking is transferred into the rotor, rather than being absorbed by a softer pad (because the harder pad is a more effective insulator and resists thermal energy transfer). Heating up your rotors more than 'normal' like this also contributes to your "wobble" problem in two ways. Not only does the excessive heat transferred to the rotors accelerate the process of them developing high spots/warping, but is also compounded as the hard pads grind the rotor thinner and thinner... that thinner rotor with less mass will heat up more quickly (and ultimately get even hotter) than a thicker rotor with more mass... further accelerating and aggravating the warping and "wobble"... so on and so forth.

The SC uses a 2 piston floating caliper design for the front brakes. (Did you read my previous reply - #2 in this thread - posted the same day that you created the thread??)

Question: Did you break in the pads at all when you first had them installed?

Also, I'm curious... if you don't track or autocross your car, what motivated you to install drilled and slotted rotors in the first place?

 

Mbodall, thanks for the lengthily reply!

I went for the different rotors and pads as I thought I would do a little track or autocross, turned out not to be the case. I also was looking for more initial bite on the brakes during normal driving, which I got. In hindsight, crossed/drilled is a bit of an overkill, i could have achieved similar results with different pads for the average drive.

Now as you mentioned it, i don't think i paid attention to break-in the pads after installation. I must do the next time, off to clublexus/google/youtube to see how.

 

 

Just one question, did you follow the proper Bedding procedure? Not following the bedding procedure can cause problems like this.

As to drilled rotors. Yes they really make no difference in daily driving, but damn they look great ! I assume you have wheels on your SC that show them off.

 

 

Btw I have a set of front and rear drilled and slotted rotors for sale that are bolt on for the SC430, all years. Just FYI for anyone interested.

 

Here is an article that outlines why drilled and or slotted rotors are of no benefit to a street car. I am posting a link to the article and I have copied the most definitive paragraph discussing the issue. Please remember that the companies that sell the drilled and or slotted rotors are not unbiased. There is no unbiased evidence that I can find that states there would be any difference in feel or performance for an SC430. In fact, there is evidence that you may actually degrade your braking performance with lower mass rotors. They do look cool however. I stated years ago on this forum that a friend of mine is a sales rep at the local Mercedes dealership and some of their high performance cars have drilled and slotted rotors stock. He has always said the techs here locally laugh about how customers think they are getting something special when they see this. Total marketing, nothing more.

https://www.good-guys.com/hotnews/te...-brake-rotors/

"It is the experience based opin*ion of every single brake expert I have consulted, that the loss of rotor mass due to drilling and slotting creates more brake loss than any possible gains due to degassing or faster cooling of the surface area. There is no better authority on hot rod brakes than Ralph Lisena at ECI. Ralph agrees that practical street driven vehicles rarely encounter the high heat conditions that make drilled or slotted rotors beneficial from a strictly functional standpoint."

 

The best upgrade for a better brake feel is to get stainless steel brake lines.

 

100% agree. Drilled and slotted rotors may likely benefit a car being tracked/raced where brakes are run at high temps and racing style (high temp) pads are changed out frequently. For street driving I suggest folks install high quality solid rotors to get good balanced performance (brakes working well cold or hot and wet or dry) with additional benefit of solid rotors being more robust and durable.